1. Field of the Invention
This invention relates to precise adjustment indicator holders and, more particularly, to precise adjustment indicator holders which use a. pair of generally parallel facewise opposed arms capable of being pivotally movable relative to one another to achieve a precise adjustment of a work piece relative to a work tool.
2. Brief Description of Related Art
It is common in the machine tool industry to use a precise adjustment indicator holder in order to position a work piece relative to a work tool such as, for example, a rotating bit of a milling machine, or the like. Usually, a rough adjustment is initially made, frequently by sight, to position a work tool relative to a work piece.
In particular, in tramming operations, that is where a work piece, such as a sheet of metal, is being cut or milled by an active cutting member, precise adjustment of the work piece is frequently required. This is particularly true where the work piece results in a product designed for close tolerance operation. In the case of milling operations, criticality of position may be required to a very fine tolerance, e.g. {fraction (1/10,000)} of an inch, or more. Therefore, it is quite important to ensure that the work piece is properly positioned prior to commencement of a cutting operation.
In many machining operations and other machine forming operations and, particularly, in milling operations, even a slight degree of error in the actual machine cutting operation can result in a work piece which has an error in tolerance. In many cases, this error in tolerance can render the work piece to be virtually useless for its intended purpose. Consequently, precise adjustment of a work piece with respect to a cutting member or other work member can be of significant importance.
In most cases, the indicator involved and which is to be held for purposes of precise adjustment may be a dial test indicator, namely a gauge, which may show a positioning of a machine tool with respect to a work piece. The spindle or collet of the machine tool is frequently referred to as a quill, as aforesaid. The indicator holder typically employs a quill clamp, that is a C-clamp secured to the quill, generally perpendicular to the axis of the quill. In many cases, an articulated arm extends from that clamp to the work piece and carries the indicator thereon.
The indicator holder provides an advantage in set-up of the machine tool. In this way, machine tools, such as a milling bit or other tool, can be mounted on the spindle or collet of the tool and located at a precise distance with respect to the work piece. In this way, errors which might otherwise occur in the machining operation can be avoided.
These indicator holders are frequently referred to as “minindicol indicator holders” or, otherwise, as “indicol indicator holders”. There are several disadvantages of the present commercially available indicator holders.
One of the primary disadvantages of prior art devices is the fact that almost all of such indicator holders are constructed with two or more articulated arms. In this case, each of the arms are connected to one another in somewhat of a cantilevered fashion. It may be appreciated that in the actual operation of the machine tool, even during tests or set-up procedures, vibrations will result. These vibrations can actually affect the positioning of the articulated arms, even to a slight degree and, hence, this can affect the positioning of the work tool relative to the work piece.
Even if the length of the adjustable arm in these commercially available indicator holders is not substantial, they are frequently designed so that they are not capable of use in close quarters. Unfortunately, the positioning of the indicator holder may be such that it is difficult to avoid interference with the machine tool and any surrounding immovable structure.
One of the currently available techniques used to avoid this problem is to provide several differently sized indicator holders. This, unfortunately, necessarily adds to the cost of the indicator holder system which is used and, hence, that cost is translated into the final cost of the work piece.
Even if the length of the articulated arms in the conventional minindicol indicator holder is not substantial, these indicator holders tend to twist, even to a slight degree. Again, this slight degree can result in a significant positioning error of the work tool with respect to the work piece. It may be appreciated that even a slight twisting action can result in the manufacture of a part which does not meet the required tolerances.
In short, there is no conventional indicator holder which overcomes these numerous disadvantages associates with each of the prior art indicator holders.